Methods of applying so-called “non-stick” coating materials for a variety of applications have long been of interest. Such applications have included the production of non-stick cookware, improving the wear resistance of joints under load, and stain resistant appliances, among others. More recently, such materials have been investigated for use in applications where fingerprint-resistance is desirable (e.g., touch-activated or touch-interactive devices).
By virtue of their designed “non-stick” nature, it traditionally has been difficult to apply these materials to a substrate such that the non-stick material sticks or remains on the substrate, particularly when the substrate materials were not compatible with the coating materials. To overcome these inherent difficulties, methods of bonding non-stick agents to metal or glass have been developed. For example, some of these methods include the use of compatibilizing agents (e.g., a primer). Mechanical solutions such as roughening the surface of the substrate also have been used to improve the adhesion of non-stick materials to a surface.
By way of illustration, according to one such method, the adhesion of polytetrafluoroethylene (PTFE), such as that sold by DuPont using the trademark TEFLON, or other non-stick coating materials on cookware or bakeware can be improved by first roughening the surface of the cookware or bakeware. This roughening can enable improved adhesion of a primer coating to the surface of the cookware. The primer can then be applied in a manner that retains the roughened surface structure. The PTFE or other non-stick material resin can then be applied to the primed, roughened surface. Subsequently, the resin-coated article can be heated to a temperature above the glass transition temperature (Tg) of the PTFE or other non-stick material resin. This thermal treatment physically entraps the resin layer over the primer and within the roughened portion of the surface.
It should be noted that, while the non-stick material may adhere to a primer using such methods, there is no covalent bonding of the non-stick coating to the substrate surface. Thus, these methods can be unsuitable for applications where frequent user or tactile interactions with the coated surface occur. That is, as a user interacts with or contacts such a coated surface, it is possible that at least a portion of the coating delaminates or becomes otherwise removed.
In addition, the use of mechanical roughening and/or primers or other agents that render the non-stick material compatible to a given surface can result in non-transparent and/or hazy articles. While these technologies may be acceptable for applications where optical properties are of minimal concern, they would not be adequate for applications where properties such as optical transparency, optical transmission, haze, or the like are important.
There accordingly remains a need for technologies that provide surfaces with improved compatibility and/or adhesion with non-stick materials. It would be particularly advantageous if such technologies could produce coated articles that did not diminish the optical qualities of the surface itself and/or that exhibit high wear resistance against user interactions. It is to the provision of such technologies that the present disclosure is directed.